Nature of the prismatic dark interstitial material in Portland cement clinker

The prismatic dark interstitial material in Portland cement clinker is essentially identical with the stable solid solution phase in the system C₃A-NC₈A₃; with rapid cooling, however, metastable extension of the solid solution series takes place, which is the prevailing mechanism of formation of the prismatic phase in works clinkers of low alkali content. The presence of SiO₂ in the interstitial material favors the metastable formation by enhancing the supercooling of the liquid phase in clinker.     

Microwave-promoted burning of Portland cement clinker

A new method of burning Portland cement clinker is studied. The microwave sintering is adopted after the raw meal is heated to certain temperature in an electric furnace. The experimental results show that after the raw meal is heated at a low electric heating temperature (1000-1200 °C) and then further sintered with microwave for 1 to 2 min, Portland cement clinkers can be formed. The f-CaO contents of the clinkers are 1-2%. It has also been found that the higher the temperature of the samples put into the microwave cavity, the shorter the time needed for microwave burning. When the temperature is up to 1300 °C, the sample needs to be heated by microwave for only 40 s, and the f-CaO content decreases to 0.65%. It has been proved by the experiments that (1) the new burning technique can greatly increase the forming speed of Portland cement clinkers, (2) Fe₂O₃ can enhance the microwave clinkering. XRD patterns of the clinkers show that their mineral compositions and the characteristic XRD peaks are similar to those of clinkers by conventional burning method.     

氧化镁对硅酸盐熟料的影响

韶峰水泥集团公司拥有Φ３０ｍ×１４５ｍ华新窑一台,Φ４０／３５／４０ｍ×１４５ｍ湘乡窑三台及Φ４０ｍ×４３ｍ窑外分解窑一台,规模为年产水泥２０２万ｔ,生产工艺条件完善,原燃材料质量比较稳定。通过多年对公司湿法回转窑熟料质量的探讨、总结发现:硅酸盐熟料中ＭｇＯ含量在２０%以下较合理;在２０%～２６%时,熟料强度呈无规律波动;而在３０%左右时,熟料强度大多呈下降趋势。本文就ＭｇＯ对熟料的烧成、晶体结构及强度的影响作探讨分析。１熟料ＭｇＯ含量与强度的关系本公司１９８８～１９９４年的熟料ＭｇＯ含量在１７%～３０%的…     

铝酸盐水泥熟料对粉煤灰硅酸盐水泥性能的影响

以铝酸盐水泥熟料、硅酸盐水泥熟料和粉煤灰为原料,探讨了掺加少量铝酸盐水泥熟料对硅酸盐水泥及粉煤灰硅酸盐水泥复合体系水化、凝结和硬化性能的影响。结果表明,在硅酸盐水泥及粉煤灰硅酸盐水泥中掺加铝酸盐水泥熟料,可以明显缩短水泥的初、终凝时间,但复合体系的需水量增加;掺加少量铝酸盐水泥熟料(≤3%)可明显提高硅酸盐水泥的早期强度,但后期强度(28d)有所降低;当铝酸盐水泥熟料的掺量达5%时,水泥的各龄期强度均明显降低。少量铝酸盐水泥熟料掺加到粉煤灰硅酸盐水泥中,复合体系的各龄期强度都明显提高,且早期强度的提高幅度较大。     

Portland cement clinker, granulated slag and by-pass cement dust composites

Three blends of slag cement were prepared, namely 70/30, 50/50 and 30/70 mass% of Portland cement clinker and granulated slag, respectively. Each blend was mixed with 2.5, 5.0, 7.5 and 10.0 mass% by-pass cement dust. The physical properties of cement pastes were studied, including setting times, electrical conductivity and fluidity. The results indicated that the rheological properties of Portland cement clinker were enhanced by partial replacement by granulated slag. By-pass cement dust affects the rheological properties of Portland cement clinker/granulated slag composites and depends on its amount as well as mix composition. The increase in the amount of by-pass cement dust increases the required water of normal consistency. The setting time of Portland slag cement paste was extended with the increase in slag content. The addition of 2.5 mass% by-pass cement dust to M.1 (70 mass% Portland cement clinker/30 mass% granulated slag) and M.2 (50 mass% Portland cement clinker/50 mass% granulated slag) retards the initial and final setting time, whereas it accelerates the final setting time of M.3 (30 mass% Portland cement clinker/70 mass% granulated slag). The presence of by-pass cement dust affects the location and height of the conductivity peaks. By increasing the by-pass cement dust from 2.5 to 7.5 mass%, the conductivity maximum increases. With further addition (10.0 mass%), the height of the conductivity maximum decreases.     

硅石在中热硅酸盐水泥熟料生产中的应用

中热硅酸盐水泥熟料生产对原材料要求较严格,但是因周边矿产资源紧缺,导致原有生产用重要硅质材料较难采购,为解决这一问题,采用了硅石进行中热硅酸盐水泥熟料生产.结果表明,利用硅石作为硅质材料生产的中热硅酸盐水泥,碱含量低,水泥后期强度增长好,水化热低.     

The manufacture of Portland cement clinker in a spouting bed

A process is proposed for the production of Portland cement clinker in a spouting bed.     

锰对硅酸盐水泥熟料煅烧的影响

通过高温差热分析、ＸＲＤ、高温显微镜分析、ＳＥＭ、ＥＰＭＡ以及测定ｆＣａＯ等方法研究了ＭｎＯ２对硅酸盐水泥熟料煅烧的影响。试验结果表明,锰主要分布在中间相,随着ＭｎＯ２外掺量的增多,熟料中铁相含量增多,Ｃ３Ａ及Ｃ３Ｓ含量减少,液相大量出现的温度升高。当ＭｎＯ２掺量小于２０％,煅烧温度高于１４００℃时,ＭｎＯ２对生料的易烧性影响不大;当煅烧温度低于１４００℃时,ＭｎＯ２使得生料的易烧性变差。ＭｎＯ２外掺量越多,生料易烧性越差。ＭｎＯ２没有矿化作用,它的存在抑制了ＣａＦ２的助熔及矿化作用。     

Waste fuels: their effect on Portland cement clinker

Nowadays, different kinds of industrial wastes are increasingly used in the clinkering process by the cement industry, with the aim of taking advantage of their energy content or confining unsuitable substances. This work evaluates the physicochemical characteristics of the clinkers obtained after incorporating three different wastes in different proportions: two of them with energetic capacity—trade marked waste fuel and waste carbon of petroleum—and the third that would be confined—pyrolitic carbon.The fusion temperature of the mixtures, the differential thermal analysis and the thermogravimetric analysis (DTA/TG) during clinkering and after hydration, the specific surface area at the same milling times, X-ray diffraction (XRD) and mechanical strength of the pastes elaborated with a water/cement 0.4 relation were analyzed. The results obtained were compared to those of the clinker obtained without additions.     

利用工业副产物制备硅酸盐水泥熟料

利用重晶石尾矿、铅锌尾矿和硅钙渣复合配料煅烧硅酸盐水泥熟料。研究结果表明，用式种类工业副产物能显著改善水泥生料易烧性，加速水泥熟料的形成，提高水泥熟料的强度，尤其是早期强度，1d抗压强度可达20MPa以上，可用此种配料工艺生产早强水泥。     

Effect of recrystallization on the characters of alite in Portland cement clinker

Alite, as well as belite, undergoes recrystallization during clinkering and grows large at the expense of small crystals. The growth is more noticeable in the direction perpendicular to (0001) than in the direction parallel to it. The crystals that are initially basal tablets become massive granules with the pyramidal faces well-developed. The recrystallization causes a considerable decrease in the concentration of the foreign ions in solid solution and thus occasionally lowers the crystal symmetry of elite to triclinic. These observations give evidence that the chemical composition of alite depends on its kinetics of crystallization from the interstitial melt.     

MnO2对硅酸盐水泥熟料性能的影响

利用XRD、SEM及强度测定等方法研究了MnO2 对硅酸盐水泥熟料性能的影响。结果表明 ,当MnO2 掺量小于2 0 %、煅烧温度高于1400℃时 ,MnO2 对熟料的抗压强度影响不大 ,可生产出优质水泥 ;当煅烧温度低于1400℃时 ,熟料的强度下降 ,且MnO2 外掺量越多 ,强度下降越明显 ,特别是3d和7d强度。     

The AFm phase in Portland cement

The AFm phase of Portland cements refers to a family of hydrated calcium aluminates based on the hydrocalumite-like structure of 4CaO·Al₂O₃·13-19 H₂O. However OH⁻ may be replaced by SO₄²⁻ and CO₃²⁻. Except for limited replacement (50 mol%, maximum) of sulfate by hydroxide, these compositions do not form solid solutions and, from the mineralogical standpoint, behave as separate phases. Therefore many hydrated cements will contain mixtures of AFm phases. AFm phases have been made from precursors and experimentally-determined phase relationships are depicted at 25 °C. Solubility data are reported and thermodynamic data are derived. The 25 °C stability of AFm phases is much affected by the nature of the anion: carbonate stabilises AFm and displaces OH and SO₄ at species activities commonly encountered in cement systems. However in the presence of portlandite, and as carbonate displaces sulfate in AFm, the reaction results in changes in the amount of both portlandite and ettringite: specimen calculations are presented to quantify these changes. The scheme of phase balances enables calculation of the mineralogical balances of a hydrated cement paste with greater accuracy than hitherto practicable.     

The structure of alite in Portland cement clinker — TEM evidence

In the examination of alite in Portland cement clinker by transmission electron microscopy, the dominant structure found was that described by Jeffery (1). Twinning on the pseudomirror plane of the monoclinic structure has been found. This provides an explanation for some weak extra X-ray reflections reported by Jeffery (1). A transformation to a new lattice occured when alite was heated in the electron microscope. Microstructural defects and diffraction effects not accounted for by the Jeffery lattice are discussed.     

镁渣替代石灰石配料烧制硅酸盐水泥熟料

实验证明,镁渣可改善生料的易烧性;在镁渣参与配料的生料中,掺加HBZ或HPZ后,促进了fCaO的吸收,能大幅度改善生料易烧性。在同时掺有1.0%HBZ和1.5%HPZ时,熟料3d和28d抗压强度比空白样分别提高38.3%和12.2%;用镁渣替代20%石灰石烧成的硅酸盐水泥熟料3d和28d强度分别可以达到40.8MPa和65.2MPa。     

Crystallization of the molten phase in portland cement clinker

Crystallization of a liquid similar to that present in Portland cement at clinkering temperatures has been studied. Its composition (in wt %) is CaO = 54.8, Aℓ₂O₃ = 22.7, Fe₂O₃ = 16.5, SiO₂ = 6.0. Prolonged crystallization or slow cooling yields the equilibrium phases: C₃A, ferrite close to C₄AF, and C₂S. With more rapid cooling or with static crystallization at lower temperatures, metastable phases form. The most important is a hitherto-unreported cubic polymorph of C₃A having a_o 3.9 Å. It is designated “proto-C₃A’ to distinguish it from ordinary cubic C₃A.     

生料细度对硅酸盐水泥熟料烧成的影响

研究了在高饱和比、高硅率的体系内,生料细度及对应细度筛余物中f-SiO2含量对硅酸盐水泥熟料烧成的影响。结果表明:在同一率值范围内,生料越细,熟料中w(f-CaO)越低,易烧性越好;生料中f-SiO2含量越高,易烧性越差,熟料中f-CaO含量越高;当0.2mm方孔筛筛余中w(f-SiO2)含量低于0.5%时,物料的颗粒尺寸愈小,反应界面和扩散截面增加,反应产物层厚度减少,熟料的烧结过程容易进行,熟料的亚微观结构中各矿物分布均匀,晶体大小适中;当0.2mm方孔筛筛余中w(f-CaO)高于0.5%时,各矿物分布不均匀,形成单一B矿区域,A矿形成数量明显减少。     

利用硅锰渣和锡渣烧制硅酸盐水泥熟料

0 引言 在立窑水泥生产中,金属尾矿和工业废渣单掺或复掺配料生产硅酸盐水泥熟料已经得到广泛应用,例如铅锌尾矿、锡渣、铜渣等, 但是用硅锰渣配料生产水泥熟料还未见报道.广西某厂附近有冶炼硅锰合金和金属锡的厂家,每年排放数万吨废渣.笔者在该厂进行技术服务期间,利用硅锰渣和锡渣双掺配料,在该厂Φ3m×11m盘塔式机立窑上生产出了早期强度高的熟料,取得了显著的效果.     

钢渣对硅酸盐水泥熟料形成的影响研究

研究了钢渣代替铁质原料配料对于硅酸盐水泥熟料形成和熟料性能的影响。研究结果表明,钢渣在煅烧温度低于1300℃时对生料易烧性没有促进作用,但是当煅烧温度在1350℃以上时,钢渣对生料易烧性和阿利特的形成均有促进作用。钢渣对熟料岩相结构的影响主要在于钢渣掺入后熟料中阿利特矿物颗粒大小和分布更加均匀,包裹物减少。     

A monoclinic tricalcium aluminate (C3A) phase in a commercial Portland cement clinker

Several commercial Portland cement clinkers have been studied to determine the polymorphic modification of the C₃A present. Various modifications of C₃A were identified and one of the clinkers contained the rare monoclinic polymorph which was particularly unusual as it appeared to be stabilised by potassium rather than sodium. XRD and IR spectroscopy have been used to compare its features with those of the other polymorphs. Possible mechanisms of crystal modification occurring in these clinkers are suggested.